1. Field of the Invention
The present invention relates to a hands-free telephone apparatus for adding a hands-free telephone function to a telephone set.
2. Description of the Related Art
There is a telephone conversion style called “hands-free conversion” for a user using a telephone set.
A hands-free telephone conversion is a conversion using a telephone set with the aid of a microphone and a speaker, which are disposed outside of the telephone set, for inputting transmitting voice and outputting received voice, respectively. Here, an apparatus which is provided with a speaker for emitting received voice and a microphone for picking up voice to be transmitted from the telephone set in order to add the above-described hands-free telephone functions to a mobile phone (called a “cellular phone” as well) is called a hands-free telephone apparatus. The apparatus is mainly installed in a vehicle, and is used to enable a driving user to carry out hands-free telephone conversion using a mobile telephone (for example, Japanese Unexamined Patent Application Publication No. 2000-52886).